feat: Add support for multiple route tables to public and intra subnets

[KevinSnyderCodes]

Description

Support for multiple route tables when creating public and intra subnets.

Motivation and Context

Guarantee that the used route table for public and intra subnets on creation is different when a boolean variable is set to true. Motivation from issue https://github.com/terraform-aws-modules/terraform-aws-vpc/issues/1020

Breaking Changes

No breaking changes, as the variables are optional and defaulted to false.

How Has This Been Tested?

• [ ] I have updated at least one of the examples/* to demonstrate and validate my change(s)
• [ ] I have tested and validated these changes using one or more of the provided examples/* projects

• [x] I have executed pre-commit run -a on my pull request

Changes were tested in a staging environment where existing public and intra subnets and route tables existed. Multiple route tables were enabled for both public and intra subnets. The existing route tables and associations were successfully updated and network traffic continued to flow as normal.